Terminal clamp for a battery terminal post

ABSTRACT

A terminal clamp for a battery terminal post including first and second relatively movable jaws defining between them a passage for receiving a battery terminal post, and a screw-operated clamping arrangement for closing the first and second jaws about the terminal post, in use, to grip the post against the action of a resilient restoring force urging the jaws apart, the screw-operated clamping arrangement including first and second components in screw-threaded arrangement with one another, the first component being held against rotation relative to the jaws, the second component having a frusto-conical cam surface cooperable with corresponding part frusto-conical cam surfaces of the jaws, whereby rotation of the second component relative to the first component and the jaws causes rotational and axial movement of the frusto-conical cam surface of the second component relative to the part frusto-conical surfaces of the jaws either to close the jaws or to release the jaws.

BACKGROUND OF THE INVENTION

The present invention relates to a terminal clamp for connecting anelectrical cable to a terminal post of a vehicle battery.

U.S. Pat. No. 5,088,941, German Patent No. 3811629 and UK PatentApplication No. 2287587 each disclose a screw-operated battery terminalclamp comprising a pair of jaws defining between them a passage forreceiving a battery terminal post, and screw-operated clamping means forclosing the jaws against a resilient restoring force, in use, to gripthe post. In each case, the clamping means includes an inclinedgenerally rectilinear cam surface on each jaw and cooperating inclinedrectilinear cam surfaces on a component movable relative to the jaws bythe screw action, either in a direction to cause the cam surfaces tocoact to close the jaws about the terminal post in use, or to releasethe jaws to open under said resilient restoring force.

A problem encountered with such arrangements is that after beingoperated to hold the jaws closed, the cam surfaces may bind together sothat release of the screw action is ineffective to release the jaws. Itis an object of the present invention to provide a terminal post clampwherein this problem is obviated.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a terminal clampfor a battery terminal post comprising first and second relativelymovable jaws defining between them a passage for receiving a batteryterminal post, and a screw-operated clamping arrangement for closingsaid first and second jaws about the terminal post, in use, to grip thepost against the action of a resilient restoring force urging the jawsapart, said screw-operated clamping arrangement including first andsecond components in screw-threaded arrangement with one another, saidfirst component being held against rotation relative to said jaws, saidsecond component having a cam surface cooperable with corresponding camsurfaces of said jaws, said cam surfaces being surfaces of revolution,or parts thereof, centred on the axis of said screw-threaded arrangementwhereby rotation of said second component relative to said firstcomponent and said jaws causes rotational and axial movement of said camsurface of the second component relative to said cam surfaces of saidjaws either to close the jaws or to release the jaws.

It will be recognised that as the cam surfaces are forced to rotaterelative to one another while moving axially to effect clamping orrelease, then the cam surfaces cannot bind together to frustrate releaseof the jaws in response to a corresponding rotation of said secondcomponent.

Preferably said cam surfaces are frusto-conical.

Desirably said first component comprises a captive bolt.

Desirably said second component comprises a nut in threaded engagementwith the shank of said bolt.

Preferably said jaws are united at one end and carry said cam surfacesadjacent their opposite ends, said post receiving recess being definedintermediate said cam surfaces and said one end.

Preferably a conductive lead is electrically connected to said jawsadjacent their united end.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further described, by way of example, withreference to the accompanying drawings in which;

FIG. 1 is a plan view of a terminal clamp for use on a battery terminalpost according to one example of the present invention, with part of theclamping mechanism omitted;

FIG. 2 is a side view of the terminal clamp shown in FIG. 1;

FIGS. 3a and 3 b are side views of a screw-threaded bolt suitable foruse with the terminal clamp of FIG. 1;

FIG. 4 is a plan view of a threaded nut for use with the bolt of FIG. 3;

FIG. 5 is a side view of the screw-threaded nut of FIG. 4, shownpartially in section;

FIG. 6 illustrates a stage in the assembly of the various components.

DETAILED DESCRIPTON OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1 and 2, the terminal clamp 10 comprises a firsthollow cylindrical end region 12 open at its free end 12 a. Integrallyconnected to said cylindrical end region 12, remote from the end 12 a,are first and second clamping jaws 14 united with the region 12 by anend region 16. The jaws 14 are mirror images and are spaced apart by agap 20 which extends continuously from the common first end region 16 toa free second end region 22 of each jaw 14. The clamp has a first face24, uppermost in use, and an opposite second face 26. A terminal post(not shown) which the terminal clamp 10 is to engage is frusto-conicalhaving a small taper angle. Adjacent the end region 16 of the clamp 10,the jaws 14 define between them a correspondingly frusto-conical passage27 extending through the clamp 10 with the larger diameter end of thepassage 27 at the face 26 of the clamp 10. Adjacent the end regions 22of the jaws 14, the jaws define between them a cylindrical passage 29having its axis parallel to that of the passage 27 and opening at thefaces 24 and 26 respectively. Intermediate the free ends of the jaws andthe passage 27 the upper surface 24 is cut away or otherwise shaped todefine an upwardly extending frustum of a cone coaxial with the passage29 and divided by the gap 20. The frustum has a cone angle of around 60°and it can be seen that each jaw thus carries a respective upstandingpart frusto-conical surface 28. A locating recess 32 is formed in theface 26 of each of said jaws 14, opposite said frustum.

Referring now to FIGS. 3a and 3 b, bolt 40 comprises a cylindrical shank42, one end of which is integrally formed with a head in the form of across piece 44. Said cross piece 44 has a substantially rectangularcross section as viewed in FIG. 3a, and a trapezoidal cross-section asviewed in FIG. 3b. The cylindrical shank 42 has a diameter less thanthat of passage 29 (FIG. 1) to permit the jaws to close withoutrestriction. The width of cross piece 44 is slightly less than that ofthe locating recess 32 (FIG. 2). The cylindrical shank 42 has ascrew-threaded region 46 extending from a free second end 48 of shank 42towards said cross piece 44.

Referring now to FIGS. 4 and 5, nut 50 comprises a hexagonal nut 52having a screw-threaded bore 53 designed to mate with the screw-threadedregion 46 of bolt 40 (FIGS. 3a and 3 b) and an integrally formed skirt54. Said skirt has a cylindrical outer surface 56, an inner surface 58which defines a frusto-conical recess 60 the cone angle of whichcorresponds with that of the frustum defining the surfaces 28 and whichflares outwardly from the screw-threaded bore 53, and an annular endportion 62.

Referring now to FIG. 6, in use, an electric cable 70 (shown in part) isinserted into the recess in the end region 12 which is then crimped,soldered, welded or otherwise arranged to hold the cable in place and tomake electrical contact thereto. The shank 42 of the bolt 40 is insertedthrough the passage 29 from face 26 of the clamp 10, such that a portionof the screw threaded region 46 of the shank 42 extends beyond face 24and the cross piece 44 is seated in the locating recess 32. The assemblyis then placed on the terminal post 72 of a vehicle battery 74 (shown inpart) such that the post 72 is located in passage 27 and the cross piece44 of the bolt 40 is held in its locating recess 32 by an upper surface74 a of the battery 74. The nut 50 is then screwed onto the bolt 40which is held in its locating recess 32 against counter-rotation. As thenut 50 is tightened, the jaws 14 are drawn closer together, causing theterminal post to be gripped progressively more tightly therebetween.

If removal of the clamping element 10 is required, for example formaintenance or replacement of the battery 74, the above process isreversed. This is a simple procedure even if there is corrosion betweensurfaces 58 of the nut 50 and 28 of the clamping component 10, sinceloosening of the nut 50, which is facilitated by the bolt 40 being heldin its locating recess 32 against counter-rotation, inevitably resultsin both axial and rotational movement of the surface 58 relative to thesurface 28, thus breaking any binding of the two surfaces and freeingthe jaws 14 to spring apart, releasing their grip on the terminal post72.

It will be understood that while the provision of a cross-piece 44 andcorresponding recesses 32 in the jaws is a convenient arrangement toinhibit rotation of the bolt 40, other arrangements for locking a boltagainst rotation relative to the jaws are possible, for example the boltcould have a hexagonal head received in corresponding recesses in thejaws. Moreover alternative forms of nut 50 can be used, for example wingnuts or socket headed nuts provided with an appropriate recess 60 couldbe utilised.

As will be apparent the cam surfaces 28, 58 could be other taperingsurfaces of revolution centred on the axis of the bolt shank 42, forexample part spherical.

What is claimed is:
 1. A terminal clamp for a battery terminal postcomprising first and second relatively moveable jaws defining betweenthem a passage for receiving the battery terminal post, and ascrew-operated clamping arrangement for closing said first and secondjaws about the terminal post, in use, to grip the post against aresilient restoring force urging the jaws apart, said screw-operatedclamping arrangement having an axis extending generally parallel to theaxis of said passage for receiving the battery terminal post, and saidclamping arrangement including first and second components inscrew-threaded arrangement with one another, said first component beingheld against rotation relative to said jaws, said second componenthaving a cam surface cooperable with corresponding cam surfaces of saidjaws, said cam surfaces being surfaces of revolution, or parts thereof,centered on the axis of said screw-threaded arrangement whereby rotationof said second component relative to said first component and said jawscauses rotational and axial movement of said cam surface of the secondcomponent relative to said cam surfaces of said jaws either to close thejaws or to release the jaws.
 2. The terminal clamp as claimed in claim1, within said cam surfaces are frusto-conical.
 3. The terminal clamp asclaimed in claim 1, wherein said first component comprises a captivebolt.
 4. The terminal clamp as claimed in claim 3, wherein said secondcomponent comprises a nut in threaded engagement with the shank of saidbolt.
 5. The terminal clamp as claimed in claim 1, wherein said jaws areunited at one end and carry said cam surfaces adjacent their oppositeends, said post receiving recess being defined intermediate said camsurfaces and said one end.
 6. The terminal clamp as claimed in claim 5,wherein a conductive lead is electrically connected to said jawsadjacent their united end.
 7. A terminal clamp for a battery terminalpost comprising first and second relatively moveable jaws definingbetween them a first passage for receiving the battery terminal post,the first passage having an axis, said first and second jaws togetherdefining an exterior cam surface spaced apart from the passage, a secondpassage being defined between the first and second jaws proximate theexterior cam surface and having an axis generally parallel to the axisof the first passage, said terminal clamp further including ascrew-operated clamping arrangement configured to engage the exteriorcam surface of the jaws to close said first and second jaws about theterminal post, to cause said first and second jaws to move towards oneanother to grip the post against a resilient restoring force urging thejaws apart, said screw-operated clamping arrangement including a boltconfigured to pass through the second passage, and a nut configured forscrew-threaded arrangement with the bolt, said nut having an interiorcam surface engageable with the exterior cam surface of said jaws, saidnut including a threaded aperture having an axis, said cam surface ofsaid nut having an axis coaxial with the axis of the threaded aperture,wherein, in operation, rotation of said nut relative to said bolt in afirst direction causes rotational and axial movement of said cam surfaceof the nut relative to said cam surfaces of said jaws to close the jawsand rotation of said nut relative to said bolt in a second direction,opposite the first direction, causes rotational and axial movement ofsaid cam surface of the nut relative to said cam surfaces of said jawsto release the jaws.